US3914817A

US3914817A - Web cleaning apparatus

Info

Publication number: US3914817A
Application number: US421326A
Authority: US
Inventors: Thomas W Lindsay
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1973-12-03
Filing date: 1973-12-03
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: FR2252878A1

Abstract

A device for cleaning photographic film including a pair of tacky low durometer cleaning rollers. A film to be cleaned is manually passed between and compresses the rollers to transfer dust particles thereon to the rollers, and then contacts a conductive brush to remove electrostatic charges caused by separation of the film from the rollers. The rollers may be cleaned periodically by passing between them a thin cleaning board having higher surface tack than the rollers.

Description

United States Patent 1191 Lindsay WEB CLEANING APPARATUS [75] Inventor: Thomas W. Lindsay, Minneapolis,

Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn.

22 Filed: Dec. 3, 1973 21 Appl. No.: 421,326

52 US. Cl. 15/3; 15/15; 15/100; 29/132 51 1111. C1 ..B08B 6/00; B08B 11/00;

G03D 15/00 [58] Field of Search l5/1.5, 3, 100, 104 A;

[56] References Cited UNITED STATES PATENTS 5/1957 Hausdorf 15/100 5/1960 Bolton et a1. 15/3 14 1 Oct. 28, 1975 3,682,690 8/1972 Amos et al 15/104 A X 3,837,952 9/1974 Mogford 15/104 A X FOREIGN PATENTS OR APPLICATIONS 1,077,960 3/1960 Germany 15/104 A Primary ExaminerDaniel Blum Attorney, Agent, or Firm-Alexander, Sell, Steldt & DeLal-Iunt [57] ABSTRACT A device for cleaning photographic film including a pair of tacky low durometer cleaning rollers. A film to be cleaned is manually passed between and compresses the rollers to transfer dust particles thereon to the rollers, and then contacts a conductive brush to remove electrostatic charges caused by separation of the film from the rollers. The rollers may be cleaned periodically by passing between them a thin cleaning board having higher surface tack than the rollers.

10 Claims, 5 Drawing Figures US. Patent Oct. 28, 1975 FIG. 4

WEB CLEANING APPARATUS CROSS REFERENCE TO RELATED APPLICATION A continuation-in-part application, Ser. No. 525,098 filed Nov. 19, 1974, includes most of the disclosure in this application, together with claims based in part on the disclosure in this application.

BACKGROUND OF THE INVENTION This invention relates to devices for cleaning sheet material, and in one aspect to devices for removing dust particles from photographic film.

Thorough removal of dust particles from photo graphic film such as a negative is necessary to produce high quality prints particularly when an enlarged print is to be made.

Prior art photographic film cleaning devices are known, illustrative examples include those described in US. Pat. Nos. 3,128,492, 3,117,333, 3,453,681 and 3,644,953. All of these devices include means for removing dust particles from photographic film, and some include electronic or nuclear means for neutralizing charges on a cleaned photographic film to restrict its attraction for dust particles in the air. While these devices vary in their effectiveness, they are all sufficiently complex so as to be too expensive for use by the average amateur photographer. Thus amateur photographers have typically resorted to the use of compressed gas, such as from a can of Freon, to blow particles from a photographic film to be processed. Thorough cleaning by this technique is highly dependent upon the operators ability to direct the gas over every portion of the film, and even when this is carefully done, the dust is blown into the air where a portion of it may again settle on the cleaned film.

SUMMARY OF THE INVENTION The present invention provides a simple and effective device for removing dust from photographic film which collects the particles removed from a cleaned film, removes static electrical charges caused by the cleaning process, and is sufficiently inexpensive so as to be economically available to the average amateur photographer.

According to the present invention there is provided a device for cleaning photographic film including a pair of cylindrical rollers each having a periphery defined by a tacky, elastic, resilient low durometer material. The rollers may be manually rotated to propel a negative to be cleaned through the nip therebetween and are spaced so that the layers of tacky material will slightly compress on the opposite surfaces of the film and adhere particles on the film to the surfaces of the rollers. A brush of fine conductive carbonaceous filaments is positioned adjacent the rollers to contact a negative being cleaned and remove static electrical charges therefrom, thereby restricting attraction between the cleaned negative and particles in the air. A thin cleaning board coated with a pressure sensitive adhesive having a surface tack which is much greater than the surface tack the rollers is provided. The cleaning board may periodically be moved between the rollers to remove collected particles from their surfaces. If not removed, such collected particles could partially mask the roller from a negative being cleaned and restrict the cleaning ability of the rollers.

The rollers each have a surface layer of material such as a synthetic polymer which has a surface tack or adhesion sufficiently high to transfer dust particles from a phtographic film, (referred to herein as tacky) but which material will not transfer to a photographic film being cleaned. The polychloroprene elastomer sold under the trade designation Neoprene is the preferred material.

The surface tack of this preferred material was tested by preparing a cylindrical test roller, 3.25 inches long, 0.75 inches in diameter, weighing 59.5 grams, and having a 0.16 inch thick surface layer of the preferred material which had a Shore A durometer value of 20, and a surface finish under 20 microinches. This test roller was placed on a properly supported planar hard polyester sheet of a photographic film. The sheet was inclined about an axis parallel to that of the roller. In repeated tests, the roller did not roll down the sheet until the sheet was inclined at an angle of at least 3 to 6. When the test roller was coated with talcum powder, it rolled down the sheet when the sheet was inclined at an angle of less than one-half a degree.

The roller should have a surface finish which is smoother than 16 to 20 microinches to afford intimate complete line contact across the surface of a photographic film between the rollers.

Rollers having thin surface layers or coatings of polymers having a Shore A durometer value of up to are suitable for cleaning planar photographic films. How ever, the surface layers of polymer preferably are over one-sixteenth inch thick and have a Shore A durometer value of less than about 20 so that the device will clean both planar films such as negatives, and photographic slides of the type having a photographic film laminated in a surrounding frame which frame projects from both surfaces of the film (e.g. conventional 35 millimeter lantern slides). A surface layer of polymer having a Shore A durometer value of 15, a thickness of at least 4; inch thick, and an outside diameter of inch can be pressed into the opening in the frame of a slide to clean the photographic film therein within about 0.005 to 0.007 inches of the frame, even at its comers.

The pressure sensitive adhesive on the cleaning board should have a surface tack which greatly exceeds that of the rollers to insure transfer of all collected particles from the roller to the cleaning board, but should not comprise an adhesive that will adhere excessively to or transfer to the rollers. The board preferably comprises tape (single or double coated) with a low tack pressure sensitive adhesive, and wound about a stiff backing sheet with an adhesive side out. The use of double coated tapes restricts possible delamination between the wraps of tape. A suitable tape should have a peel test strength of at least 5 ounces per inch when tested in accordance with test procedure No. PSTC-l as specified by the Pressure Sensitive Tape Counsel, 1201 Wauhegon Road, Glenview, Illnois 60025. Tapes with higher peel test strengths can be used. An example of one suitable tape which has a peel test strength of 25 to 30 ounces per inch is the low tack tape sold under the trade designation Scotch brand double coated tape No. Y402 by Minnesota Mining and Manufacturing Company, St. Paul, Minnesota.

The conductive brush should comprise a multiplicity of fine conductive filaments which make complete intimate contact with the surface of the photographic film, and are sufficiently supple to prevent scratching of the negative. Preferred is a brush of the type disclosed in US. Pat. No. 3,757,164, the disclosure whereof is incorporated herein by reference. Briefly that brush comprises a support from which project filaments about 0.00034 inch in diameter of thermochemically converted regenerated cellulose fiber starting material which has been impregnated with a salt composition and subsequently carbonized to provide conductive fiber material of predominantly amorphous carbon, which is sold under the trade name Pluton and designated I-I-25 Roving by Minnesota Mining and Manufacturing Company, St. Paul, Minnesota. These filaments have been found to essentially remove static electrical charges on both surfaces of a photographic film even though the brush contacts the film on only one side. Such filaments projecting about 0.4 inch from their support and contacting the negative about 0.3 inch from their support provide a thorough wiping action between the filaments and the photographic film, without exerting sufficient force to scratch the negative. Preferably the filaments contact the photographic film on its lower side so that any filaments that may separate from the brush will not be deposited on the clean photographic film.

BRIEF DESCRIPTION OF THE DRAWING The invention will be further described with reference to the accompanying drawing wherein like numbers refer to like parts in the several views, and wherein:

FIG. 1 is a view in perspective of a device for cleaning photograhic film according to the present invention;

FIG. 2 is a sectional view of the device of FIG. 1 taken approximately along the lines 2-2 and illustrating the cleaning of a coil of photographic film between a pair of tacky rollers on the device;

FIG. 3 is a sectional view of the device of FIG. 1 taken approximately along the lines 2-2 and illustrating the use of a cleaning board to clean the tacky rollers;

FIG. 4 is a sectional view taken approximately along the lines 44 of FIG. 1; and

FIG. 5 is an enlarged fragmentary view of a bar on the device of FIG. 1 for supporting a coil of photographic film to be cleaned.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 there is shown a cleaning device according to the present invention and generally designated by the numeral 10. The device comprises a pair of rotatably mounted axially parallel rollers 12 and 14 each having a soft surface layer of a polymeric material which provides a tacky peripheral surface for the roller. The roller 12 may be manually rotated via a knob 16 to drive a film 17 to be cleaned through the nip between the rollers 12 and 14 (FIG. 2) so that dirt particles on the film 17 will be transferred to the surfaces of the rollers 12 and 14. A brush 18 of conductive carbonaceous fibers or filaments is mounted adjacent one side of the rollers 12 and 14 so that the fibers will contact and remove static electrical charges from a negative subsequent to its cleaning. A thin cleaning board 20 is provided which has a higher tack on its major surfaces than the surface tack of the rollers. The cleaning board 20 may periodically be driven between the rollers 12 and 14 (FIG. 3) to transfer dirt collected on the rollers 12 and 14 to the cleaning board 20.

The device 10 comprises a frame 24 having a base plate 26 supported on rubber feet 28 on which base plate 26 the cleaning board 20 may be stored when not in use, and spaced parallel upstanding side walls 30 between which the rollers 12 and 14 are journaled. A shaft 32 of the lower roller 12 extends through one side wall 30 and has the knob 16 fixedly attached at its outboard end.

The side walls 30 mount the upper roller 14 for movement away from the lower roller 12 to facilitate movement of a photographic film or the cleaning board 20 therebetween, and means are provided for biasing the upper roller 14 toward the lower roller 12 to provide the pressure required for intimate contact between the rollers 12 and 14 and a photographic film being cleaned. The side walls 30 each have a horizontal slot 34 between the rollers 12 and 14 which is between a bottom portion 36 of the side wall 30 in which the bottom roller 12 is journaled and a top portion 38 in which is journaled the top roller 14. The

portions

36 and 38 are joined together over only a small area at one end of the slot 34 and the material of the side wall 30 (e.g. Delrin) is sufficiently flexible that said small area will provide a hinge to allow movement between the

portions

36 and 38 and the rollers 12 and 14.

Each top portion 38 has a socket 40 in which a coil spring 42 is retained under the head of a screw 43 (FIGS. 1 and 4). The screw 43 passes through the spring 42 and a clearance hole in the top portion 38, and threadably engages the bottom portion 36. The springs 42 bias the upper roller 14 toward the lower roller 12, and the upper roller 14 may move away from the lower roller 12 against the bias of the springs 42 to accommodate a film or the cleaning board 20 between the rollers 12 and 14.

The cleaning board 20 has a width only slightly less than the distance between the side walls 30 to afford full width cleaning of the rollers 12 and 14. As best seen in FIG. 3, the board consists of a sheet of stiff material 44 such as plastic about which is wrapped a length of pressure sensitive adhesive tape 46 (which may be single or double coated) with an adhesive side out. The wraps of tape 46 are each cut across one end of the sheet 44 so that when the adhesive on an outer wrap of tape becomes so loaded with dirt particles that it will no longer efficiently clean the rollers 12 and 14, the outer wrap can be conveniently peeled away to expose a clean inner wrap.

The brush 18 is of the type disclosed in US. Pat. No. 3,757,164 and is constructed according to the method disclosed in US. Pat. No. 3,689,117, the disclosures whereof are incorporated herein by reference. The brush comprises a multiplicity of resilient supple, conductive carbonaceous filaments 48 projecting from and adhered in a metal support 49.

The device includes means for moving the brush 18 away from the nip of the rollers 12 and 14 during movement of the cleaning board 20 therebetween (FIG. 3) to prevent adhering the brush filaments 48 to its lower surface 22.

As is best seen in FIGS. 2 and 3, the brush 18 is pivotally mounted about the shaft 32 for the lower roller 12 by a bracket 50 at each of its ends. The brush 18 may be pivoted between a normal position established by abutment of an edge on one bracket 50 against a pin 52 fixed to the frame 24 (FIG. 2) with the filaments 48 positioned to contact the adjacent surface of a film driven between the nip of the rollers 12 and14; and a second position with the brush fibers 48 spaced from a planar object moving between the rollers 12 and 14 (FIG. 3). A spring 54 is attached between the frame 24 and one of the brackets 50 and provides means for biasing the brush 18 to its normal position. The brackets 50 each have a narrow shoe 56 closely spaced from the adjacent side wall 30. The shoes 56 each are shaped to provide a camming surface aligned to be contacted by a planar object moving through the nip of the rollers 12 and 14 with one edge positioned closely adjacent the side wall 30, and to cause movement the brush 18 to its second position as the end of the planar object moves across the upturned ends of the shoes 56 opposite the rollers 12 and 14. Since the device is designed to clean films which are more narrower in width than the distance between the side walls 30, such films if somewhat centered between the side walls 30 will not contact the shoes 56 to move the brush 18 to its second position (FIG. 2). The cleaning board 20, however, is only slightly less narrow in width than the distance between the side walls 30 so that it will contact the shoes 56 and move the brush 18 to its second position as the cleaning board passes between the rollers 12 and 14 (FIG. 3).

The device 10 also includes means for unrolling a coiled length of film 17 to be cleaned by the rollers 12 and 14. A specially shaped rod 60 (intended to be stored between an opposed pair of recesses 62 in the side walls 30 as illustrated in FIG. 1 when flat films or negatives are being cleaned) may be positioned between a pair of recesses 64 in the side walls 30 adjacent the inlet side of the rollers 12 and 14 as is shown in FIG. 2. The rod 60, as is best seen in FIG. 5, has nested narrow and wide generally centrally located pairs of notches 66 and 67. The notches 66 and 67 are aligned generally transverse to the axis of the rod 60. Each pair of notches 66 or 67 is spaced to engage the edges of a film for which it is sized, and to bow the center of that film outwardly away from the rod 60. The coil of film 17 is placed as is illustrated in FIG. 2 so that the longitudinal are caused in the film by engagement of its edges in the notches 66 or 67 straightens the transverse arc of the film 17 in the coil. This causes the film to leave the coil in a tangent thereto to be pulled between the rollers 12 and 14, while the coil is supported only by edge contact with the length of film in the pair of notches 66 or 67. This simple support eliminates the need of a reel to support the coil of film (which coil if unsupported would be pulled against the rollers 12 and 14).

As an illustrative, non-limiting example, a device 10 having rollers 0.7 inch in diameter, 3% inches long with a 0.16 inch thick surface layer of 15 durometer polychloroprene elastomer (i.e. neoprene) biased together with springs exerting a combined force of 12 pounds will efficiently clean planar photographic film (e.g. conventional photographic negatives) and will clean 35 millimeter slides with 3/64 inch thick frames within 0.005 to 0.007 inch of the frame.

Having thus described the present invention with reference to a preferred embodiment, what is claimed is:

l. A device for cleaning photographic film, comprising:

a frame;

first and second cylindrical rollers rotatably mounted on said frame in axially parallel relationship, the periphery of each of said rollers being defined by a layer of tacky elastic resilient polymeric material having a peripheral surface finish finer than 20 microinches, said rollers being spaced so that a said film in the nip therebetween will contact and slightly compress the layer of polymeric material on each roller; drive means for affording rotation of at least one of said rollers to propel a said photographic film through said nip toward one side of said rollers whereby dust particles on said photographic film will be transferred to said polymeric material; a brush comprising a multiplicity of projecting fine resilient conductive carbonaceous filaments;

means for mounting said brush on said frame with said filaments positioned to make contact withone surface of a said photographic film propelled through said nip in an area adjacent said one side of said rollers, whereby electrostatic charges on a cleaned photographic film will be neutralized; and

cleaning board comprising a thin sheet of stiff material having opposite major surfaces of a width approximately the same as the length of said rollers, and a coating of pressure sensitive adhesive over said major surfaces, said coating being firmly adhered to said sheet of stiff material and having a greater surface tack than said layer of polymeric material on said rollers, said board being adapted to be propelled through said rollers via said drive means whereby dust particles accumulated on said rollers from photographic film will be transferred to said cleaning board.

2. A device according to claim 1, wherein said layer of tacky polymeric material is more than 0.06 inch thick and consists of polychloroprene having a Shore A durometer value of less than about 20.

3. A device according to claim 1, wherein said conductive filaments are formed of thermochemically connected regenerated cellulose fiber starting material which has been impregnated with a salt composition and subsequently carbonized to provide conductive fiber material of predominantly amorphous carbon, and have a diameter of about 0.00034 inch.

4. A device according to claim 1, wherein said means for mounting said brush mounts the brush on said frame for movement between said position with said conductive filaments positioned to make contact with a said photographic film propelled through said nip, and a second position with said conductive filaments spaced from a planar object moving through said nip, and said device further includes biasing means for biasing said brush toward said position with said conductive filaments positioned to make contact with a said photographic film propelled through said nip and means adapted for engagement with an edge of said cleaning board to move said brush to said second position against the influence of said biasing means upon movement of said cleaning board through said nip.

5. A device according to claim 1 wherein said device includes a bar mounted on said frame generally axially parallel with said rollers adjacent their side opposite said first side, the surface of said bar having at least one pair of opposed transverse notches adopted to engage the edges of a film to be cleaned and spaced apart axially of said bar a distance slightly less than the width of the film to be cleaned to support and bow the film away from the bar about an axis normal to the bar, thereby straightening the film in a direction normal to the axis of the rod so that the film will tangentially leave a coil of the film adjacent the bar.

6. A device for cleaning photographic film, comprising:

a frame; first and second cylindrical rollers rotatably mounted on said frame in axially parallel relationship, the periphery of each of said rollers being defined by a layer of elastic resilient polymeric material having a peripheral surface with a finish finer than microinches said peripheral surfaces being adapted to have a substantially greater adhesion to dust particles than the surfaces of a said photographic film, and said rollers being spaced so that a said photographic film in the nip therebetween will contact and slightly compress the layer of resilient material on each roller; drive means for affording rotation of at least one of said rollers to propel a said photographic film through said nip toward one side of said rollers whereby dust particles on said photographic film will be transferred to said resilient material; a brush comprising a multiplicity of projecting resilient conductive filaments; means for mounting said brush on said frame with said filaments positioned to make contact with one surface of a said photographic film propelled through said nip in an area adjacent said one side of said rollers, whereby electrostatic charges on a cleaned photographic film will be neutralized; and a cleaning board comprising a thin sheet of stiff material having opposite major surfaces of a width approximately the same as the length of said rollers, and a tacky coating over said major surfaces, said coating being firmly adhered to said sheet of stiff material and having a greater surface tack than said layer of resilient material on said rollers, said cleaning board being adapted to be propelled through said rollers via said drive means whereby dust particles accumulated on said rollers from photographic film will be transferred to said cleaning board.

7. A device according to claim 6, wherein said layer of polymeric material is more than 0.06 inch thick and has a Shore A durometer value of less than about 20.

8. A device according to claim 6, wherein said means for mounting said brush mounts the brush on said frame for movement between said position with said conductive filaments positioned to make contact with a said photographic film propelled through said nip, and a second position with said conductive filaments spaced from a planar object moving through said nip, and said device further includes biasing means for biasing said brush toward said position with said conductive filaments positioned to make contact with a said photographic film propelled through said nip and means adapted for engagement with an edge of said cleaning board to move said brush to said second position against the influence of said biasing means upon movement of said cleaning board through said nip.

9. A device according to claim 6, wherein said cleaning board comprises a multiplicity of layers of tape, with each layer of tape comprising a coating of pressure sensitive adhesive, being disposed with said coating of adhesive out around the major surfaces of said sheet of stiff material and being severed adjacent one edge of said major surfaces to facilitate removal of the outer layer of said tape after dust particles have been transferred from said rollers to the adhesive coating thereof, thereby exposing a clean coating of pressure sensitive adhesive.

10. A device according to claim 6, wherein said device includes a bar mounted on said frame generally axially parallel with said rollers adjacent their side opposite said first side, the surface of said bar having at least one pair of opposed transverse notches adapted to engage the edges of a coiled film to be cleaned and spaced apart axially of said bar a distance slightly less than the width of the coiled film to be cleaned to support and bow the film away from the bar about an axis normal to the bar, thereby straightening the film in a direction normal to the axis of the rod so that the film will tangentially leave the coil adjacent the bar.

Claims

1. A device for cleaning photographic film, comprising: a frame; first and second cylindrical rollers rotatably mounted on said frame in axially parallel relationship, the periphery of each of said rollers being defined by a layer of tacky elastic resilient polymeric material having a peripheral surface finish finer than 20 microinches, said rollers being spaced so that a said film in the nip therebetween will contact and slightly compress the layer of polymeric material on each roller; drive means for affording rotation of at least one of said rollers to propel a said photographic film through said nip toward one side of said rollers whereby dust particles on said photographic film will be transferred to said polymeric material; a brush comprising a multiplicity of projecting fine resilient conductive carbonaceous filaments; means for mounting said brush on said frame with said filaments positioned to make contact with one surface of a said photographic film propelled through said nip in an area adjacent said one side of said rollers, whereby electrostatic charges on a cleaned photographic film will be neutralized; and cleaning board comprising a thin sheet of stiff material having opposite major surfaces of a width approximately the same as the length of said rollers, and a coating of pressure sensitive adhesive over said major surfaces, said coating being firmly adhered to said sheet of stiff material and having a greater surface tack than said layer of polymeric material on said rollers, said board being adapted to be propelled through said rollers via said drive means whereby dust particles accumulated on said rollers from photographic film will be transferred to said cleaning board.

6. A device for cleaning photographic film, comprising: a frame; first and second cylindrical rollers rotatably mounted on said frame in axially parallel relationship, the periphery of each of said rollers being defined by a layer of elastic resilient polymeric material having a peripheral surface with a finish finer than 20 microinches said peripheral surfaces being adapted to have a substantially greater adhesion to dust particles than the surfaces of a said photographic film, and said rollers being spaced so that a said photographic film in the nip therebetween will contact and slightly compress the layer of resilient material on each roller; drive means for affording rotation of at least one of said rollers to propel a said photographic film through said nip toward one side of said rollers whereby dust particles on said photographic film will be transferred to said resilient material; a brush comprising a multiplicity of projecting resilient conductive filaments; means for mounting said brush on said frame with said filaments positioned to make contact with one surface of a said photographic film propelled through said nip in an area adjacent said one side of said rollers, whereby electrostatic charges on a cleaned photographic film will be neutralized; and a cleaning board comprising a thin sheet of stiff material having opposite major surfaces of a width approximately the same as the length of said rollers, and a tacky coating over said major surfaces, said coating being firmly adhered to said sheet of stiff material and having a greater surface tack than said layer of resilient material on said rollers, said cleaning board being adapted to be propelled through said rollers via said drive means whereby dust particles accumulated on said rollers from photographic film will be transferred to said cleaning board.